1. Field of the Invention:
This invention relates to a recording and/or reproducing apparatus of the kind using a disc shaped record bearing medium such as a rotating magnetic sheet or disc.
2. Description of the Prior Art:
In a recording and/or reproducing apparatus of the kind using a disc shaped rotating record bearing medium such as a rotating magnetic sheet or disc, a center core is attached to the middle part of the magnetic sheet. In rotating the magnetic sheet, this center core is fitted onto a spindle which is arranged to be rotated by a sheet rotating motor. However, if the fitted engagement of the center core and the spindle is loose, the magnetic sheet tends to fail to normally rotate during recording or reproduction and, if the engagement is too tight, the magnetic sheet cannot be readily mounted on the spindle. In view of this, there has been proposed a magnetic coupling method, in which the spindle is provided with a permanent magnet and the center core with a soft magnetizable plate, so that the two can be reliably coupled by having the soft magnetizable plate attracted by the permanent magnet. However, even in accordance with the magnetic coupling method, it is still difficult to have the center core always accurately positioned on a reference surface, such as a flange surface of the spindle. Therefore, this method fails to ensure that the magnetic sheet is always in a prescribed confronting state relative to the recording and/or reproducing head. Further, in the case of a still picture recording and/or reproducing apparatus which severely requires mounting precision, it is necessary to use a force of several hundred grams for mounting the center core on the spindle. Hence, this requirement necessitates use of a large magnet, which hinders efforts to reduce the size and weight of the apparatus. In another method of the prior art for this purpose, the magnetic disc or sheet is pressed by means of a pressing mechanism against the spindle in such a manner as in the case of floppy disc devices. A device employing this method is arranged to rotate while the above-stated mechanism is left in a state of pressing the magnetic disc. This arrangement causes an increase in load on the motor and also results in uneven disc rotation.
To eliminate this inconvenience, there has been proposed an apparatus of the type having temporary pressing means for mounting a record bearing medium on rotating drive means. The apparatus of this type has been disclosed, for example, in U.S. patent application Ser. No. 591,383 filed Mar. 20, 1984, and U.S. patent application Ser. No. 637,392 filed Aug. 3, 1984 by the inventors of the present invention.